JPH0857183A - Vibration control apparatus for zigzag sewing machine - Google Patents

Abstract

PURPOSE: To enable vibration control of a sewing machine in either horizontal or vertical directions regardless of the sewing speed. CONSTITUTION: A rotational shaft 21 that rotates synchronously with rotation of the main shaft of a sewing machine is provided with a rotor 22. A movable weight 23 is movably disposed in a groove formed on the rotor 22, through an elastic member provided therebetween. As the rotor 22 rotates together with the sewing operation, the movable weight 23 is moved against the elastic member by centrifugal force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-stabilizing device for a zigzag stitch sewing machine which prevents a table or the like supporting the sewing machine body from vibrating when the zigzag stitch sewing machine is driven.

[0002]

2. Description of the Related Art Generally, a zigzag stitch sewing machine as shown in FIG. 4 is known. This zigzag stitch sewing machine M
In addition to a well-known needle bar lifting mechanism (not shown) for vertically moving the needle bar NL, a needle bar rocking mechanism 1 for horizontally rocking the cloth in the direction orthogonal to the cloth conveying direction is provided. ing.

That is, in this zigzag stitch sewing machine M, the sewing machine main shaft 2 supported in the sewing machine arm Ma and the sewing machine lower shaft (not shown) held in the sewing machine bed Mb are rotated by driving a sewing machine motor (not shown). While the sewing needle N is moved up and down, the sewing machine is rotated, and the like, while the sewing machine lower shaft is rotated, the cam plate 3 is rotated together with the cam shaft 3 and the roller 4a is fitted in the cam groove 4a of the cam plate. The connecting rod 5 moves the needle swing link 6 up and down.

Since the needle swinging link 6 is connected to a swinging link 7 which is rotatably supported about a fulcrum 7a, the vertical movement of the needle swinging link 6 includes a horizontal component. , Its horizontal component is transmitted to the swing rod 9 connected through the joint 8. Further, a needle bar holding base 9 that supports the needle bar NL so as to be vertically movable is fixed to one end of the swing rod 9, and the needle bar holding base 10 moves in the horizontal direction together with the swing rod 9. As a result, the needle bar NL swings in the horizontal direction orthogonal to the cloth conveying direction.

As described above, the needle bar NL performs the ascending / descending movement using the rotation of the sewing machine main shaft 2 as a driving source and the swinging movement using the rotation of the sewing machine lower shaft as a driving source, and as shown in FIG. Staggered stitches are formed that are alternately bent in the left-right direction with respect to the transport direction. The stitch S1 shown in FIG. 5A is formed by switching the swing direction of the needle bar NL for each stitch.
A point-stitched zigzag stitch is shown, and a stitch S2 shown in FIG. 7B represents a 4-point stitched zigzag stitch formed by switching the swing direction of the needle bar every 3 stitches.

By the way, the above-mentioned zigzag stitch sewing machine M
Then, the needle swing mechanism 1 for swinging the needle bar NL and the like
Since the various members inside swing in the horizontal direction as described above, the inertial force generated by the swing motion acts on the sewing machine table or the like that holds the sewing machine. When the oscillation frequency in the horizontal direction coincides with the natural frequency of the sewing machine table, the table and the sewing machine resonate and vibrate with an extremely large amplitude, resulting in a significant hindrance to the sewing work.

Therefore, at present, it is proposed to prevent the above-mentioned vibration by attaching an anti-vibration device including a counterweight 10 as shown in FIG. 6 to the cam plate 3.
It has been implemented. In this vibration isolator, the center of gravity G of the cam plate 4 is set to a position deviated from the rotation center O by the counterweight 11, as shown in FIG. An unbalanced force can be generated to prevent horizontal vibration. That is, in this vibration isolator, when the inertial force F1 of the needle bar or the like acts in the arrow X1 direction as shown in FIG. 6A, the unbalanced force M1 due to the eccentricity of the center of gravity G is It acts in the X2 direction, which is the opposite of the direction, and as shown in FIG.
When the inertial force F2 acts in the X2 direction due to
The unbalanced force F2 due to the eccentric center of gravity G acts in the X1 direction.

Therefore, the inertial force in the horizontal direction due to the needle bar NL or the like is canceled by the unbalanced force due to the counterweight 10, and the vibration in the horizontal direction is greatly reduced. For this reason,
Even when the oscillation frequency of the needle bar NL matches the oscillation frequency of the sewing machine table, a large horizontal vibration does not occur in the sewing machine and the sewing machine table.

[0009]

As described above, in the conventional vibration isolator described above, the counterweight 11 provided on the rotary cam 4 is counterbalanced.
However, it is effective in reducing horizontal vibration of the sewing machine table, etc., but it may also act to rejuvenate vibration in the vertical direction, which may hinder work. It was That is, when the vertical natural frequency of the sewing machine table and the vibration frequency of the unbalanced force by the counterweight 10 match, the sewing machine table and the sewing machine are in a resonance state and vibrate vertically with a large amplitude. There was a problem in that workability was significantly reduced and work comfort was also greatly impaired. However, since the vertical vibration generated by the weight is small when the sewing machine table and the sewing machine are not in a resonance state, the vibration does not adversely affect the work.

The present invention has been made in view of the above-mentioned problems of the prior art. The zigzag stitch sewing machine is capable of preventing vibration of the sewing machine in both horizontal and vertical directions regardless of the sewing operation speed. The purpose of the present invention is to provide an anti-vibration device.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a needle bar that moves up and down in synchronization with the rotation of a sewing machine spindle, and a needle bar that swings the needle bar horizontally in synchronization with the rotation of the sewing machine spindle. A swinging mechanism, and a rotating body that rotates in synchronization with the rotation of the sewing machine main shaft about a horizontal axis that is orthogonal to the swinging direction of the needle bar,
A groove portion that is formed to extend toward the center of rotation O of the rotating body, a movable weight that is movably accommodated in the groove portion, and the movable weight has a predetermined position in the groove portion when the rotating body is stopped. And an elastic holding body that elastically holds the movable weight so as to be located at.

[0012]

In the present invention, when the needle bar moves horizontally by the needle bar swinging mechanism, the rotating body rotates in synchronization with this, and the movable weight resists the elastic force of the elastic holding member by its centrifugal force. The center of gravity of the rotating body automatically changes in accordance with the rotation speed of the rotating body, and when the position does not coincide with the rotation center O of the rotating body, an unbalanced force is applied to the rotating body. Occurs. Then, by appropriately setting the phase of the movable weight provided on the rotating body, it is possible to cancel out the unbalanced force and the horizontal inertial force generated by the needle bar or the like. It is also possible to make the center of gravity of the rotating body coincide with the rotation center O when the oscillation frequency of the needle bar reaches a frequency that coincides with the vertical natural frequency of the sewing machine table. By doing so, it is possible to prevent vertical vibration of the sewing machine table or the like.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
It will be explained based on. It should be noted that the same or corresponding parts as those of the above-mentioned conventional technique are designated by the same reference numerals, and detailed description thereof will be omitted.
The vibration isolator of the zigzag stitch sewing machine according to this embodiment has a rotary shaft 21 that rotates in synchronization with a known sewing machine lower shaft.
A rotating body 22 as shown in FIG. 2 is provided.

The rotary shaft 21 extends along the axial directions Y1 and Y2 perpendicular to the swinging directions X1 and X2 of the needle bar in the zigzag stitch sewing machine. The same camshaft as the camshaft 3 shown in the above-mentioned prior art is used.

The rotating body 22 has a disk shape, and its central portion is fixed to the rotating shaft 21, and a cylindrical groove 22a is formed from its peripheral surface portion to the central portion. A circular movable weight 23 is movably accommodated in the cylindrical groove 22a, and the movable weight 23 is
A coil spring 24 for constantly urging the coil toward the center is inserted. The coil spring 24 has the groove 22a at one end.
The cover 22b that covers the opening 22a1 of the above is designed to prevent outward projection, and its elasticity always causes the movable weight 24 to be pressed against the peripheral surface of the rotary shaft 21. There is. In addition, here, the rotating body 2
A rotary cam similar to the rotary cam 4 shown in the above-mentioned prior art is used as 2, and the connecting rod 4 is provided on one side surface thereof.
A cam groove 22c for inserting the roller 4a (see FIG. 4) is formed. However, this rotary cam is formed thicker than the one conventionally used as described above because of the necessity of forming the groove portion.

The center of gravity G of the rotating body 22 is
It is formed so as to be located on the extension of the center line L2 of the groove portion 22a, and the center of gravity G has the following positional relationship with the swing position of the needle bar NL. That is, when the needle bar NL is rocked to the leftmost side by the needle bar rocking mechanism or the like, as shown in FIG. 2A, the center of gravity G rotating in the counterclockwise direction about the cam shaft 21 rotates. When the needle bar NL is positioned right above the center O and the needle bar NL is swinging to the rightmost, the center of gravity G is set right below the center O of rotation as shown in FIG. There is.

The vibration isolator of the zigzag stitch sewing machine in this embodiment is constructed as described above, and when the sewing needle N and the like swings in the vertical and horizontal directions as the sewing machine main shaft 2 rotates, the sewing machine lower shaft is rotated. The rotary shaft 21, which is a cam shaft, rotates in conjunction with the rotation of the rotary body 21, which rotates the rotary body 22, which is a rotary cam. Due to the rotation of the rotating body 22, a centrifugal force is applied to the movable weight 23, and the coil spring 24 is moved outward while compressing the coil spring 24 against the elastic force, and the centrifugal force of the movable weight 23 and the elasticity of the coil spring 24 are moved. The position of the movable weight 23 in the radial direction is held when the force and the force match.

By the movement of the movable weight 23, the rotating body 22
The center of gravity of the entire body moves from the initial state shown in FIG. 2A toward the center as shown in FIG. 2B, but at this stage, the position of the center of gravity is displaced with respect to the center of the rotating body 22. Therefore, an unbalanced force is generated in the rotating body 22.
Since the horizontal components m1 and m2 of the unbalanced force have a phase difference of 180 degrees with respect to the inertial force generated in the horizontal direction due to the swing motion of each member of the needle bar swing mechanism, the two components are mutually different. They act to cancel each other and are offset. Therefore, even if the needle bar oscillates at the same cycle as the natural frequency of the sewing machine table in the horizontal direction, the sewing machine M
The sewing machine table will not vibrate.

When the driving speed of the sewing machine is further increased, the oscillation frequency of the needle bar may coincide with the vertical natural frequency of the sewing table at a certain driving speed. At this time, if the center of gravity of the rotating body 22 is located at a position deviated from the center of rotation O and an unbalanced force is generated in the rotating body 22, the vertical component thereof becomes large due to the resonance between the sewing machine table and the sewing machine M. Amplified,
As a result, workability is significantly impaired.

However, in this embodiment, before the oscillation frequency of the needle bar NL matches the natural frequency in the vertical direction of the sewing machine table, the center of gravity G of the rotary body 22 is moved by the movement of the movable weight 23 due to the centrifugal force. Since the state coincides with the center of rotation O, the unbalanced force is not generated by the rotation of the rotating body 22, and in this state, the oscillation frequency of the needle bar NL coincides with the natural frequency of the sewing table in the vertical direction. However, vertical vibration does not occur in the sewing machine table and the sewing machine M.

As described above, in this embodiment, not only the vibration in the horizontal direction but also the vibration in the vertical direction can be completely suppressed, so that the work can be performed comfortably.

In the above embodiment, the case where the vertical natural frequency of the sewing machine table has a value higher than the horizontal natural frequency has been described as an example. However, the relationship between the natural frequencies is opposite. In some cases, as shown in FIG.
The position of 2a and the position of the center of gravity of the rotating body 23 when the rotation is stopped may be changed.

That is, the position of the groove portion 22a may be arranged in a phase different from that of the above embodiment by 180 degrees, and the position of the center of gravity of the rotating body 22 in the stopped state is the natural frequency in the vertical direction of the sewing machine table. It may be set so that the center of gravity of the rotating body 22 coincides with the center of rotation when the oscillation frequency of the needle bar coincides.

According to this, when the oscillation frequency of the needle bar reaches the natural frequency of the sewing table in the vertical direction, the unbalanced force is not generated in the rotary body 22, and the vibration in the vertical direction is eliminated. Occurrence is prevented. Even if the oscillation frequency of the needle bar is made to coincide with the natural frequency of the sewing machine table in the horizontal direction, the center of gravity of the rotating body 22 is rotated by the outward movement of the movable weight 23 as in the above embodiment. Since it is set at a position deviated from, vibration in the horizontal direction is also prevented by the unbalanced force generated during rotation.

By the way, in each of the above-described embodiments, the movable weight 23 is biased toward the center by using the compressive force of the coil spring 24 inserted in the groove portion, but as shown in the third embodiment of FIG. Alternatively, a coil spring 34 may be interposed between the movable weight 33 and the rotary shaft 21, and the extension force of the coil spring 34 may urge the movable weight 33 toward the center. In the figure, 35 is a guide for guiding the movable weight 33 so as to be movable in the radial direction, and this guide 35 is fixed to the needle swing cam 22.

As the elastic member, the coil spring 24 is used.
It is also possible to use air, oil, sponge, rubber, or any other material. FIG. 5 is a diagram showing a fourth embodiment of the present invention. In this fourth embodiment, an air damper 44 is used as an elastic member, and this also produces the same effect as each of the above-mentioned embodiments. In addition, in the first and second embodiments, the needle swing cam and the cam shaft are used as the rotary body 22 and the rotary shaft 21, but in the fourth embodiment, the rotary shaft 21 is rotated only for the vibration isolator. A body 42 is provided.

FIG. 6 is a diagram showing a fifth embodiment of the present invention. In the fifth embodiment, a rotating body 52 having a rectangular parallelepiped shape is fixed to the rotating shaft 21, a movable weight 53 is movably fitted into the rotating body 21, and the movable weight 53 is constantly rotated by a compression spring 54. It is designed to be pressed in the direction of the shaft 21, and the same effect as that of each of the above-described embodiments can be expected also by this.

A motor other than the sewing machine motor may be used as the drive source for the rotating body in the fourth and fifth embodiments, and further, a plurality of weights having various weights with respect to the rotating body may be used. By arranging in various phases, it becomes possible to cope with a complicated unbalanced force, and the present invention is not limited to the above-mentioned embodiment.

[0029]

As described above, in the vibration isolator for a zigzag stitch sewing machine according to the present invention, a rotary body is provided on the rotary shaft that rotates in synchronization with the rotation of the main shaft of the sewing machine, and the groove formed on the rotary body is elastic. The movable weight is movably accommodated through the member,
Since the movable weight is moved by centrifugal force against the elastic member due to the rotation of the rotating body accompanying the sewing operation, the inertial force caused by the swing of the needle bar during the sewing operation is Can be canceled out by the unbalanced force generated in the vertical direction, and the vertical vibration caused by the presence of the movable weight will rotate when the natural frequency in the vertical direction of the sewing machine table and the oscillation frequency of the needle bar match. Since no unbalanced force is generated in the body, it is possible to prevent vibration in the vertical direction.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a first embodiment of the present invention, in which (a) shows a state in which a needle bar is located on the rightmost side,
(B) shows the state when the needle bar is located on the leftmost side.

FIG. 2 is a partially cutaway front view showing a main part of the first embodiment of the present invention, in which (a) shows a state when rotation of a rotating body is stopped, and (b) shows a swing frequency of a needle bar. Shows a state that matches the oscillation frequency in the horizontal direction of the sewing machine table,
(C) shows a state in which the oscillation frequency of the needle bar matches the oscillation frequency in the vertical direction of the sewing machine table.

FIG. 3 is a partially cutaway front view showing a main part of a second embodiment of the present invention, in which (a) shows a state when rotation of a rotating body is stopped, and (b) shows a swing frequency of a needle bar. Shows a state that matches the oscillation frequency in the vertical direction of the sewing machine table,
(C) shows a state in which the oscillation frequency of the needle bar matches the oscillation frequency in the vertical direction of the sewing machine table.

FIG. 4 is a perspective view showing a main part of a third embodiment of the present invention.

FIG. 5 is a perspective view showing a main part of a fourth embodiment of the present invention.

FIG. 6 is a perspective view showing a main part of a fifth embodiment of the present invention.

FIG. 7 is a side view showing a needle bar swinging mechanism and the like in the zigzag stitch sewing machine.

FIG. 8 is a plan view showing a zigzag stitch, in which (a) shows a two-point zigzag stitch and (b) shows a four-point zigzag stitch.

FIG. 9 is an explanatory front view showing the vibration isolating action of the vibration isolator of the conventional zigzag stitch sewing machine, in which (a) shows the needle bar in the rightmost position and (b) shows the needle bar in the leftmost position. The respective positions are shown.

[Explanation of symbols]

 1 Needle bar rocking mechanism 2 Sewing machine main shaft 21 Rotating shaft 22 Rotating body 22a Groove 23 Movable weight 24 Coil spring (elastic member) M Staggered sewing machine NL Needle bar N Sewing needle G Center of gravity O Rotation center

Claims (3)

[Claims] 1. A sewing machine main shaft that is rotatably held in a zigzag stitch sewing machine that is held on a sewing machine table and that is rotatable by a driving force of a sewing machine motor, and a sewing machine arm in a vertical direction and in a predetermined horizontal direction. And a needle bar that is movably held and that moves up and down in synchronization with the rotation of the sewing machine spindle, and a needle bar swinging mechanism that swings the needle bar in a predetermined horizontal direction in synchronization with the sewing machine spindle. A rotating body that rotates in synchronization with the rotation of the sewing machine main shaft about an axis extending in a horizontal direction orthogonal to the swinging direction of the needle bar; and a rotating body that extends toward the center of rotation of the rotating body. Groove part, a movable weight housed in the groove part so as to be movable along the extension direction thereof, and the movable weight is elastically movable so as to be located at a predetermined position in the groove part when the rotating body is stopped. Elastic holder that holds the weight Anti-vibration device for zigzag stitch sewing machines, which is equipped with and. 2. The zigzag stitch sewing machine according to claim 1, wherein the elastic holding member is constituted by a spring having one end fixed to the rotating body side and the other end abutting against the movable weight. Anti-vibration device. 3. The vibration isolator for a zigzag stitch machine according to claim 1, wherein the spring is a coil spring housed in a cam groove.